This circular tower, measuring 10.5 metres across and rising 7.7 metres high, represents all that survives of Dunmore Castle, a medieval stronghold that may have served as the administrative centre of the manor of Dunmore. The manor itself has a fascinating history; originally granted to Heverbricht by Henry II and later confirmed by King John in 1203, it eventually fell into the hands of the de Boitler and Le Flemming families by the early 14th century. The Le Flemmings found themselves locked in a bitter dispute with Robert de Stapleton, the sheriff of Waterford, over ownership of these lands.

The castle’s architecture tells its own story of medieval defensive ingenuity. Visitors entering through the rebuilt eastern doorway, which still preserves part of its original southern door jamb, would have found themselves in a lobby overlooked by a murder hole; a grim reminder of the castle’s defensive purpose. A guardroom to the south provided additional security. The ground floor features three embrasures with single lights, their segmental arches still visible despite centuries of weathering. A particularly clever feature is the double garderobe chute that exits through the wall at the south southeast, whilst mural stairs wind upward from the lobby to reach the upper floors. The first floor, accessed through a pointed doorway and once supported on a stone rebate, contained four similar embrasures, though time has taken its toll on these openings.

Archaeologist Casey noted in 2001 that the promontory’s strategic position and the castle’s placement might indicate an even older fortification on this site, possibly a promontory fort predating the medieval structure. Whilst traces of a perimeter bank and some faint surface undulations hint at earlier activity, conclusive evidence remains elusive. By 1640, the castle had already fallen into ruin and passed into the ownership of Lord Power of Curraghmore, marking the end of its active life as a defensive structure but the beginning of its long afterlife as a romantic coastal ruin.